Conventionally, there have been known siphon jet type flush toilets as described in Patent Document 1 (Japanese Patent No. 5429688) and Patent Document 2 (Japanese Patent No. 4529178). In these conventional siphon jet type flush toilets, as illustrated in FIG. 6, there has been known the one in which a jet spout port 132 extending rectilinearly toward a center of an inlet portion 122a of a water discharge trap conduit 122 is disposed in order to perform startup of a siphon and discharge of waste efficiently by a jet spout water flow, in a flush toilet 101. A bowl section bottom surface 120a of a bowl section 120 which is connected to an outlet of the jet spout port 132 like this extends rectilinearly toward the center of the inlet portion 122a of the water discharge trap conduit 122 from the outlet of the jet spout port 132.